Re: [MedievalSawdust] Re: Vice screws ? (update)
It takes a lot of work to make a good tool, the better the tool the more work. I have a conflicting and duel line of thought on making tools and caring for tools. Tools should be appropriately respected and cared for. On the other hand, tools, all, tools, are disposable implements that are designed to make something else. Heat treatment of metal tools even today with modern alloys and furnaces that can be set for exact temperatures is still an art. What is good for one tool and tool application is not the best for another, and the perfect process for one tool and application may may need to be changed when the size of tool is the only variable that has changed. My point is don't get too caught up in heat treatment processes. A mild steel un-heat-treated blade in your screw-cutter may need to be honed more often, maybe even several times before one screw is finished but is much much easier to shape and can be done very precisely with hand files and then finished by honing. I am guessing that your planing on making a hand full of wooden screws, not several thousand. If that's the case making the blades of a high quality shape in a poorer quality metal will get the job done better that a poorly shaped m2 blade that you have ground on for hours with a small hand grinder which admittedly may last you nearly forever in all its poor quality grandeur. As both a woodworker and a smith I will say that all can be done with the right materials and a little practice. Annealing a carbon steel make it soft (so you can file it) heating and quenching makes it hard and brittle (so it will hold an edge longer) and tempering removes brittleness (so your tool doesn't brake like glass when you drop, strike, or hit something unexpectedly with it). If learning these skills are on your back burner instead of your back pocket then don't let that get in the way of your making a good tool to do the job you are doing. The job of your tool is to teach you how the tools to thread nuts and rods were made and then to make a few. It doesn't need to last forever.
I am very interested in screws (and medieval threaded fasteners in general and not just wood ones) and would like to see your documentation for the threading devices you mentioned. I have a picture of Hero's but it is confusing, and is a drawing not from a primary source.
On 11/21/2012 7:41 AM, nelsonhaynes@... wrote:My mentor told me that you would have better success cutting threads if you soak maple in linseed oil overnight.In a message dated 11/20/2012 9:50:07 P.M. Eastern Standard Time, pellison@... writes:
Thanks all that commented I really do appreciate the emails.
Here is the current status:
I got two "sample" turning blanks (3" square by a 12") one was hard maple, the other sycamore (it was cheaper for some reason). My plan to was to practice before cutting a large maple one.
I chiseled away at about 2 inches of thread on the hard maple blank, about 6 turns into the nut. The manually cut threads are pretty close to the right patch. My major diameter was too thick so that caused me to thing I had the wrong pitch.
My screwbox cutter is the wrong shape and not sharp enough, so I decided to abandon that part of the project for now. A two and a half inch major diameter screw needs two cutters. I'm not sure I'm smart enough to get that to work.
I took a short cut, a bit strange because I'm mostly a hand tool using primate. The chiseling was just too slow.
I mounted the screwbox on the mini-mill, chucked up a 60 degree 1/2" router bit, lined it up where the cutter should have been and manually turned the screw into the screwbox past the router bit. Other that some chewed up threads, that look a lot like the ones I did with a chisel they threads came out pretty decent. The will not win a beauty contest, but they are strong and hold fast. I'd like to state this process is NOT for the faint of heart, even with everything mounts securely to the table there is lots of vibration and chips flying everywhere.
The hard maple one threads are a little smoother than the sycamore. Since the maple was the one I did first, likely if I did another one it would come out better.
One thing that I did note is that you can't find a large triangular file at a home store or Menard's. So I'll be making a triangular sanding block so that I can smooth out the tooling marks and make things work a little better.
I have a Moxon vise that I make with the 6 threads/inch 1.5" screws that I have not been happy with so I decided to drill out the holes and tap them with the new manual tap since I have two fully functional screws. So far that process has gone pretty well.
I'll try and get some pictures eventually of the results.
I'll send another update in a couple of days.